1. Field of the Invention
The present invention relates to a blanking apparatus for cutting out blanks from a strip and more particularly to a programmable controlled turnblanking machine wherein a pair of blank dies each having a cutting edge are disposed on a bed in a direction in which the said strip is fed, and in order to cut the strip to predetermined shape and size by means of the cutting edges of the blank dies, the blank die located in front in the said strip feed direction is supported on the bed rotatably about its central part, while the blank die located in the rear in the said strip feed direction is supported on the bed rotatably in the same manner as in the front blank die and slidably in the said feed direction, and the blank cutting operation of the blanking apparatus is performed automatically according to a program in which are written positioning data comprising angles .theta..sub.1, .theta..sub.2 of the said rotations of both blank dies and a slide distance X of the rear blank die.
2. Description of the Prior Art
According to conventional methods for obtaining a large number of blanks such as trapezoidal or rectangular blanks of different sizes and angles from a strip, a pair of blank dies each having a cutting edge are positioned appropriately at every lot and are moved while measuring the spacing between the cutting edges according to the size of a blank to be obtained, or a gauge board is fixed removably to a bolster of a blanking machine, then locate pins are implanted into the gauge board and lugs formed on the blanking dies are brought into engagement with the locate pins.
However, a considerable degree of skill is required for moving the blank dies in conformity with the size of a blank to be obtained; besides, if the size and angle should be mistaken, it is likely that all of the blanks obtained will be useless. Further, a conveyor located between both blank dies has not been fully responsive to rotations or movements of the blank dies.
Additionally, it is difficult to firmly fix the blank dies so that their angle and position once set are not displaced by impact or the like induced by the blank cutting operation. And if this is to be realized using a conventional hydraulic mechanism, not only the entire apparatus will become very large in size but also a complicated layout of oil feed pipe will result.
In the conventional blanking dies, moreover, the time required for their mounting at every change in shape of blank is long and so in the recent multi-variety, small lot production a great decrease in operating efficiency of blanking dies is unavoidable.